kenneth l. rock, m.d.az9194.vo.msecnd.net/pdfs/100602/008.pdf · naip nlrc pyrin nlrp (nalp)...

Inflammasomes &

inflammationKenneth L. Rock, M.D.

The innate immune system uses

numerous “sensors” to detect

problems

One of the best understood is the Toll-like receptor

(TLR) system

TLRs are expressed on the cell surface or in

endosomes & monitor the environment for

pathogens

Toll-like receptors (TLR)

Structure-Function

Plasma membrane

Extra-

cellular

Intra-

cellular

Leucine-rich

repeats

Protein

interacting

domain

Recognition

Signaling

TLR recognition- LRR domains

Recognize non-mammalian structures

MembranePeptidylglycanLipoproteinLPS Lipoteichoic

Acid

Gram – Gram +



MembranePeptidylglycanLipoproteinLPS

TLR4

Lipoteichoic

Acid

Gram – Gram +




TLR4

Lipoteichoic

Acid

TLR2

Gram – Gram +




TLR4

Lipoteichoic

Acid

TLR2

Gram – Gram +

A limited number of receptors (10-11 TLR genes) – each “sees” a

different set of non-mammalian structures in bacteria, yeast, virus,

permitting recognition of a very large number of microbes.

Biochemical & structural evidence

of TLR Ligand recognition

Some of the ligand-receptor interactions have

been detected biochemically

Crystal structure shows binding to LRR

Others are not measurable (affinity too low?)

Cytosolic sensors

One subset = NOD-like receptors (NLR)

23 genes in humans

34 genes in mice

All have Nucleotide Oligomerization Domains (NOD)

All have LRR domains (in this aspect like

intracellular TLRs)

LRR

Presumed

Ligand

binding

Oligomerization

Protein

interaction

NOD

NLRs – 4 families

(based in part on C-terminal domains)

CARD

NOD

LRR

NOD

Bir

NAIP NLRC

Pyrin

NLRP (NALP)

Presumed

Ligand

binding

Oligomerization

Protein

interaction

What do they sense?

Direct binding has not been measured yet

NOD2

NLRP1 (NALP1)

NLRP3 (NALP3)

Peptidyl glycan fragments (e.g. MDP)

NOD1 Peptidyl glycan fragments (e.g. meso-DAP)

NLRC3 (IPAF) Flagellin

MDP, Anthrax lethal toxin

MDP, LTA, pore forming toxins, other

What most NLRs sense is unknown.

The C-terminal domain determines

function

CARD

NOD

LRR

BirPyrin

Presumed

Ligand

binding

Oligomerization

Protein

interaction

Homotypic interactions with adaptor and effector

molecules

Function

A small subset of NLRs stimulate IL-1

Production

CARD

NOD

LRR

NOD

Bir

NAIP NLRC

Pyrin

NLRP (NALP)

Presumed

Ligand

binding

Oligomerization

Protein

interaction

1 14

NLRP1-3IPAFS

u

# human genes

Summary of key points

2 important sets of microbial sensors are the

TLR (extracellular) and NLR (intracellular)

They have LRR regions that are thought to bind

ligands (only shown for TLR).

Their C-termini are protein-interacting domains

which determine their function

A subset of NLR participate in the generation of

IL-1

NLRs that trigger IL-1

Have C-terminal protein interaction domains

that form a complex called the Inflammasome

(more later)

We will focus on the NLRs that

trigger IL-1

But first, a primer on IL-1

Interleukin 1 (IL-1)

Discovery

Infection Fever


Discovery

Infection Endogenous pyrogen Fever


Discovery


IL-1 (also IL-6 & TNF )


Discovery


IL-1 (also IL-6 & TNF )

2 forms: IL-1 & IL-1

Generation of IL-1

Proinflammatory stimuli

IL-1 gene Pro-IL-1

(inactive)

Generation of IL-1

Proinflammatory stimuli

IL-1 gene Pro-IL-1

(inactive)

IL-1

(active)

Caspase 1

procaspase 1 (inactive)

What does IL-1 do?

IL-1R

IL-1 & IL-1

Cell

What does IL-1 do?

IL-1R

IL-1 & IL-1

Cell NFkB (inactive)

genes

active

What does IL-1 do?

IL-1R

IL-1 & IL-1

Cell NFkB (inactive)

genes

IL-1

IL-6

IL-8

TNF

MIP-1

MCP1

RANTES

eotaxin

ICAM-1

E-selectin

VCAM-1

Cytokines Chemokines Cell Adhesion

active

NF B and Inflammation

Injury/infection

TNF

Endothelial activation

Selectins

integrin activation

Integrin ligands

chemokines

IL-8Fever

IL-1

IL-6

Contribution of IL-1 to inflammation in

different settings

Autoimmunity

IL-1 receptor antagonist (IL-1Ra)

Autoimmunity

Rheumatoid arthritis patients

IL-1 receptor antagonist (IL-1Ra)

Clinical improvement

[but not as effective as anti-TNF; presumably

because in autoimmunity IL-1 is one of many

factors]

Autoinflammatory diseases

Muckle-Wells, NOMID, Familial cold

autoinflammatory syndrome, FMF

Autoinflammatory diseases

Genetic syndromes where IL-1 is over produced

Marked clinical improvement

Muckle-Wells, NOMID, Familial cold

autoinflammatory syndrome, FMF

Fever, skin, joint, ± neurological symptoms

IL-1Ra

Other settings where IL-1 plays a major

role in inflammation

Sterile cell death

Rock K et al Ann. Rev. Path: Mechanisms of Disease Vol 3:99-126 (February 2008) with permission from Annual Reviews

Neutrophils

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

3.0E+06

IL-1 is made by the host in response to cell

death

Dead cells

i.p.

Courtesy of Hajime Kono, submitted

Neutrophils

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

3.0E+06

Bkg Recipient strain

Key role of IL-1-IL-1R in death-induced

inflammation

Dead cells

i.p.

Lack IL-1

Courtesy of Hajime

Kono, submitted

Neutrophils

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

3.0E+06

Bkg Recipient strain

Key role of IL-1-IL-1R in death-induced

inflammation

Dead cells

i.p.

Lack IL-1 Lack

receptor

Courtesy of Hajime

Kono, submitted

MSU - gout

MSU-induced inflammation requires the

IL-1R

P<0.05

*

C57BL/6 IL-1R -/- PBS0

20

40

60

80

100

120

140

160

180N

eu

tro

ph

il n

um

ber(

x 1

05)

Reproduced with permission from the American Society for Clinical Investigation

Chen C et al. Journal of Clinical Investigation 116:2262-2271© 2006.

Other IL-1 dependent

inflammation

SilicaAsbestos

Alum

Amyloid aggregates

Irritant particles

Summary

IL-1 is a cytokine whose maturation

requires a cleavage by caspase 1

Mature IL-1 stimulates NFkB, a

transcription factor that controls many key

molecules in inflammation

IL-1 plays an essential role in

autoinflammatory conditions, cell death &

particle inflammation & also contributes to

autoimmune inflammation

Getting back to the NLRs…

Pyrin

NLRP3

NFkB activators

(TLR, cytokines)

Increase

Synthesis

Connecting NLRs to IL-1 production

Stimuli


CARD

Pyrin

ASC

caspase 1

Stimuli

The inflammasome

ASC

caspase 1


Stimuli

The inflammasome

The inflammasome

Unstimulated Stimulated

ASC-CFP

Courtesy of Eicke Latz

caspase 1ACTIVE


Pro-IL-1

(inactive)

Stimuli

Importance of NLRP3 to IL-1

production & inflammation

Familial cold Auto-inflammatory

syndrome

(Fever, cold urticaria, arthralgia)

Muckle-Wells syndrome

(Fever, urticaria, arthralgia, deafness,

amyloid)

CINCA (NOMID)

(Fever, urticaria, arthralgia,

neurological disease, amyloid)

Inherited inflammatory diseases

Mutation

NLRP3

How are NLRs normally

stimulated?

Remember = cytosolic molecules

NLRC4 (IPAF)

Type III & IV

secretion systems

Pannexin

(channel)

salmonella,

pseudomonas

Legionella

e.g. Flagellin

NLRC4

NLRP3 (NALP3)

Listeria lysin O

Aerolysin

maitolysin

Pore –forming toxins

ATP

K+

K+P2X7

Maybe the same model

But in addition…

Gout-associated uric acid crystals activate

the NALP3 inflammasome

Fabio Martinon, Virginie Petrilli, Annick Mayor,

Aubry Tardivel & Jurg Tschopp

Nature 2006, 440:237-241

Other particulates activate the

NLRP3 inflammasome

Wild-type NLRP3-/-

Silica Alum

+/+ -/-

Reprinted by permission from Macmillan Publishers Ltd.,

Nature Immunology Hornung V et al 2008, 9:847-856, © 2008

Yet other particles/crystals stimulate IL-1

production from M via NLRP3 (NALP3)

inflammasomes

Asbestos (Flavell)

Summary

Pyrin-domain containing NLRs assemble into

inflammasomes

Simulated inflammasomes activate caspase 1 that in

turn generates active IL-1

Gain of function mutations in these NLRs causes IL-

1 dependent autoinflammatory syndromes.

These NLRs can “sense” microbial ligands & also

somehow particles and crystals.

How can intracellular NLRP3

sense extracellular particles?

CFP-ASC

(inflammasome)

Crystals

Control Cytochalasin D

Phagocytosis of MSU

Courtesy of Eicke Latz

Is phagocytosis important for triggering

IL-1 production?

Phagocytosis is required for crystal activation of

the inflammasome

Reprinted by permission from Macmillan Publishers Ltd., Nature Immunology Hornung V et al 2008, 9:847-856, © 2008

How do internalized crystals

activate inflammasomes?

Postulated mechanism 1

NADPH

Oxidase

ROS

O2

Thyrodoxin

Thyrodoxin

binding-protein

Data for another, maybe

unifying mechanism

Visualize the fate of crystals

M

Cholera toxin B

Membrane stain

Rupture of MSU-phagosomes

Red = membrane

Green = MSUCourtesy of Eicke Latz

Conclusions

Triggering of NLRP3 inflammasomes by

particles requires phagocytosis

Some phagosomes containing crystals

(MSU+others) rupture & deliver their contents to

the cytosol

Rupture

(Common)

MSU silica Alum

Structurally

Distinct

What is NLRP3 sensing?

Particle-free sterile rupture of

lysosomes

Leu-Leu-OMe

Hypertonic

sucrose

Osmotic rupture

of vesicles

Feed to M

Rupture of lysosomes is sufficient

to activate inflammasomes

Wild type M



Leu-Leu-OMe

NLRP3-/- ASC-/-Wild type M

Rupture of lysosomes is sufficient

to activate inflammasomesM



Conclusions

Crystal containing phagosomes rupture

NLRP3 senses internal cell damage

(lysosomal rupture)

Rupture of lysosomes is sufficient to cause

NLRP3 activation

NLRP3 sensing of endosome-

phagosome rupture

This might also explain why pore-

forming toxins trigger NLRP3

How does NLRP3 sense lysosomal

rupture?

NLRP3

H+

Bafilomycin

Acidification is required

NLRP3

H+

Bafilomycin

Acidification is required

WHY?

Role for Cat B in crystal induced

inflammasome activation

Reprinted by permission from Macmillan Publishers Ltd., Nature

Immunology Hornung V et al 2008, 9:847-856, © 2008

Model

NLRP3

H+

H+

Cat B

Rupture

substrate

Medical Significance

Inflammation is a double-edged

sword

Rapid defense

RepairTissue damage

Courtesy of Ellie Crystal

Cost-benefit in sterile inflammation

Damage

Protection

Sterile inflammation leads to or

exacerbates a number of

diseases

Collateral damage after sterile cell

death

C57BL/6 IL-1R-/-

Reprinted by permission from Macmillan Publishers Ltd., Nature Medicine

Chen CJ et al 2007, 13:851-860, © 2007

Toxic

injury

Also in ischemic injury (MI, Stroke)

Crystal-based diseases

Asbestosis



Other diseases?

Maybe…..

Atherosclerosis



Consequences of atherosclerosis

16.7 million deaths from cardiovascular disease

each year. > 29% of all deaths globally and 38%

of all deaths in North America

Also:

Peripheral vascular

disease

Other ischemic

organ damage

www.nlm.nih.gov/medlineplus/ency/imagepages/19314.htma Accessed 3/10/2010.

Atherosclerosis - pathogenesis




cholesterol crystal

atherosclerosis

(inflammation)


monosodium urate

crystal

gout

(inflammation)


silica crystal

silicosis

(inflammation)

Atherosclerosis

A crystal-based disease???

Eicke Latz Hajime Kono

Peter Duewell

Franz Bauerfeind

Cherlyn Sirois

George Abela

Luigi Franchi

Gabriel Nunez

Max Schnurr

Terje Espevik

Kathryn Moore

Kate Fitzgerald

Sam Wright

Veit Hornung

nuclei (Hoechst)

macrophage (MoMa-2)

crystals (reflection)

Reg

ula

r D

iet

Hig

h F

at D

iet

X 1

2w

kApoE-/- mice

Reprinted by permission from Macmillan

Publisher Ltd., Nature Rock L et al 2010 (In Press)

Uptake of modified LDL leads to the

formation of cholesterol crystalsReprinted by permission from Macmillan Publisher Ltd.,

Nature Rock L et al 2010 (In Press)

Cholesterol crystal stimulates M s to

produce IL-1 in vitroIL

-1B

(ng/m

l)

Reprinted by permission from Macmillan Publisher

Ltd., Nature Rock L et al 2010 (In Press)

Cholesterol crystal stimulates M s to

produce IL-1 in vitroIL

-1B

(ng/m

l)

Reprinted by permission from Macmillan Publisher Ltd.,


Phagocytosis

Cholesterol crystal stimulation of IL-

1 requires:

Acidification

Plasma membrane

Free crystals

Crystals in phagosomes

Rupture of cholesterol-phagosomes

Reprinted by permission from Macmillan

Publisher Ltd., Nature Rock L et al 2010 (In Press)

Cholesterol crystal stimulation of M s to

produce IL-1 in vitro requires cathepsins



IL-1

Cholesterol stimulates IL-1 production

by the same pathway as other crystals

Cholesterol

Uric acid

Silica

Etc.

H+

CatB

Nalp3CatB

Inflammation

What about in vivo?

LDL receptor-/-High

Fat Diet

?NLRP3 IL-1

LDL receptor-/-

What about in vivo?

High

Fat Diet



?NLRP3 IL-1

What about in vivo?

LDL receptor-/-High

Fat Diet



Inflammasome role in atherosclerosis In Vivo

LDLR-/-

Inflammasome role in atherosclerosis In Vivo

LDLR-/-WT B6

ASC-/-

NLRP3-/-

IL-1AB-/-

Bone marrow

And the results …..



Summary• Cholesterol crystal appears in the early

atherosclerosis

• Cholesterol crystal stimulates macrophage / DCs

to secrete IL-1 beta, which is dependent on

phagocytosis / lysozomal acidification and damage /

CatB / CatL / NLRP3 / ASC/ Casp1.

• LDLR-/- mice with inflammasome deficient bone

marrow showed reduced atherosclerosis lesion.

• Atherosclerosis might be a crystal-based disease

Overall summary

Microbes & particles

NLR

Inflammasomes

IL-1

Inflammation

Disease

The End

kenneth l. rock, m.d.az9194.vo.msecnd.net/pdfs/100602/008.pdf · naip nlrc pyrin nlrp (nalp)...

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